ESFR's and Concrete Tee Construction

[WallyFP]

I've got a building with 19-inch deep concrete tee roof construction. Per section 8.4.6.3 of NFPA 13, ESFR sprinklers are not allowed with obstructed construction exceeding 12 inches in depth (unless installed in every channel). In my situation, that would result in less than the minimum allowable spacing.

Has anyone seen any creative ideas (other than a drop ceiling) that could possibly be used to fill the channels (at least partially) so that the 12-inch requirement can be met?

Thanks.

 

[SprinklerDesigner2]

I think you will need a suspended ceiling.

 

[cdafd]

what are you trying to protect

high piled storage ???

rack storage ??

??

have you called the manufacter and asked the question???


also if they are set up in the "tee" seems like you would have a built in deflector and the min spacing would not be an issue, of course you would have a lot of extra heads that would have to be added.


A.8.4.6.3 Storage in single-story or multistory buildings can be permitted, provided the maximum ceiling/roof height as specified in Table 8.12.2.2.1 is satisfied for each storage area.

 

[WallyFP]

Thanks cdafd.

Protection is for cartoned unexpanded plastics in open frame racks.

Per comments in the 13 handbook, "Sprinklers are required in each channel and must be located so that the MINIMUM spacing requirements of 8.12.2 and 8.12.3 are maintained"

I think based on this, sprinkelrs in each channel is not an option for channels 4 or 5-ft. apart.

 

[SprinklerDesigner2]

cdafd,

Maybe Stookey will step in but I am sure you can not use baffles with ESFR sprinklers.

I spent last week at the PGA Golf Resort in Palm Beach (tough week) getting 34 hours of CEU's with the NFSA.

One of the talks was given by Kenneth Isman, PE who is vice president of engineering for the NFSA an an alternate to Russ Fleming on the 13 committee. The lecture specifically had to do with ESFR sprinklers. Most of us always thought in terms of "beams being walls" but with ESFR sprinklers this is not the case. Ken Isman gave an example of ESFR sprinklers positioned 3'-9" on either side of a 36" steel beam and when asked most of us declared we didn't see a problem. Shocked when we were told this was wrong.

Appearantly the force of the water from ESFR sprinklers is so strong when the water impacts the top it spashes off the storage to cold shower the head on the other side of the beam.

I don't want to declare I am right or wrong but that is the way I understood it.

Stookey, help me out here?

 

[cdafd]

Ken Isman gave an example of ESFR sprinklers positioned 3'-9" on either side of a 36" steel beam and when asked most of us declared we didn't see a problem.

Interesting, than can a esfr be located within 3"9" of a wall???

I do not think any one would want to put esfr's in the tees, because of the number that would be required, even if it could be done.



8.4.6.3* ESFR sprinklers shall be permitted for use in buildings with unobstructed or obstructed construction




3.7 Construction Definitions.
3.7.1* Obstructed Construction. Panel construction and other construction where beams, trusses, or other members impede heat flow or water distribution in a manner that materially affects the ability of sprinklers to control or suppress a fire.



Ithink go back to manufuacter and ask the question first

 

[cdafd]

WallyFP

you say they are more than 12 inches in depth, but do not say the other dimension, what is the spacing between tees????

 

[SprinklerDesigner2]

cdafd,

Yes, it had to do with spacing in bays.

I don't know if it is right but I think it deserves a close check... either way I would like to know.

 

[WallyFP]

Thanks for the additional comments cdafd. The tees are 5-ft. apart - agree that even if NFPA allowed it, that's not a desired option.

Sounds like as Sprinklerdesigner2 suggested, it's probably going to be a suspended ceiling if ESFR's are going to be used.

 

[cdafd]

how many square feet are we talking about????



can they attach shhet rock to the bottom of the tees???

 

[SprinklerDesigner2]

Interesting, than can a esfr be located within 3"9" of a wall???

Can position it right up next to a wall or as close as NFPA will allow. A wall is different from a beam in this respect because the concern is "splash up" (I made that term up for lack of being able to think of a better one) resulting in cold soldering.

I wish I could have taped it because doubts are entering my mind if I heard it right. In any event I would be careful and check it out.

 

[cdafd]

maybe a good size I beam??? with good size wings???

have not looked at esfr cut sheet in awhile, and know there is a lot of do nots on them, would be interesting to see if something about beams is on it???

 

[cdafd]

the other question on the tee spacing was because

what if these tees are only two feet apart, but still over 12 deep??

at what point would the requirement kick in or not apply??? or would it apply regadless??

or would it go back to manufacture requirements???

 

[WallyFP]

My thoughts....

If the tees are less than 8-ft. or anything that results in less than 8-ft. spacing (minimum allowable) between heads with a sprinkler installed in each channel, it won't work.

That's why you either reduce the depth in the tee to less than 12-inches by filling the space (probably not feasible) or you install a suspended ceiling.

 

[cdafd]

WallyFP

IF you have a deep enough tee and stick the sprinkler head near the top od th tee it seems like the tee would ack as a baffle, and the minimum spacing would not be a problem

1. you would use a lot more heads

2. not sure if it would work on esfr, because of spray pattern and number of heads that might open

 

[WallyFP]

I think that's the concern. Too many heads open up if you reduce the spacing. I would imagine that if you still maintained an operating area of roughly 1200 sq.ft. - you MIGHT be able to get and AHJ to accept the reduced head spacing, however, that would probably be a cost prohibitive design with ESFR heads spaced 4-ft. apart throughout a 200k sq.ft. building. It's tough to design an ESFR system for 24 heads opearating - lots of water

 

[MGXFP]

Are ESFR sprinklers essential? Can you use a CMSA sprinkler instead?

The VK592 is listed for concrete tee construction if my memory is correct. I don't think I can help you for an ESFR application with concrete tees and everything exposed.